Build It Green - Part 2

As I touched upon on Monday there are a variety of lesser championed green building techniques that tread lightly on the planet and wallet. On Monday I profiled Rammed Earth building techniques and today I touch on several others.

Despite the bad rap that straw gets from the three little pigs Strawbale buildings are cheap, easy to build and extremely energy efficient. They resemble rammed earth houses with thick walls, wide window sills and rounded corners but with additional insulation. They were first developed in the grasslands of Nebraska where there was plenty of straw and few trees. The structures are built by stacking bales of hay and then plastering the hay with plaster, stucco, or earth plaster. The resulting house is quiet (the thick walls provide natural sound resistance), warm, sustainable, and fire resistant. Because the bales of hay are so tightly wound they're exceedingly difficult to burn - a typical wood framed structure can burn in as little as 30-minutes, a Strawbale home will take 2-hours. They're also sturdy: strawbale structures from the 1800's are still standing in the US and Europe today, and strawbale structures have withstood California earthquakes while in wind tests bale structures see no movement in a sustained 75 mph gale. In addition, the United States burns or otherwise disposes 200 million tons of "waste" straw annually, releasing carbon in the process. Using this easily renewable material (straw has a one year growth/harvest season) for house building would reduce our need to destroy slower growing forests.

Cob building involves mixing clay-bearing earth with sand, straw and water to make a thick mud that can be hand sculpted into a house which is typically finished with stucco or plaster. Because of its free form Cob houses can (and do) look like just about anything. Like other earth houses the walls tend to be thick resulting in a high thermal mass; thus cob houses are cool in summer and warm in winter and more energy efficient than frame houses . Additionally, because dirt is well, dirt cheap, the houses are extremely cost-effective to build, in addition to being fire resistant, and pest resistant. . It is a very old building method -there are Cob homes still standing today in Wales that are at least 500 years old.

If while watching The Lord of the Rings you wondered to yourself how you could go about building your own hobbit hole, you're in luck such building design already exists and much like the hobbit's lifestyle, it's sustainable. Underground or Earth-Sheltered houses fall into three broad categories:

• Envelope houses which consist of a central pit courtyard open to the sky with rooms tunneling off, from the central courtyard.


• Slope houses, are essentially a conventional home cut back into the side of a hill. All the windows and doors would be on one side, while the back of the home would have no windows etc as it is cut into the hill.


• A Bermed house is a house that is dug into the ground and then covered up by dirt.

The benefit of underground construction, apart from being able to say that you live in a hobbit house, is energy-efficiency. Because the earth stays at 50 degrees year round, earth houses also maintain a consistent temperature. Depending on location and size of structure a few people and a greenhouse may provide all of the additional heating the dwelling requires even in winter. Earth sheltered houses can cut energy use by as much as 85%.

The methods which I've hi-lighted in the past two blog entries are only the tip of the alternative green building iceberg. Depending on your location, Slipform Masonry houses, Log Homes, and Earthships are additional building techniques that are not only sustainable but also affordable house building options. As we sit in the midst of an economic and ecological crisis brought about in no small part because of how we choose to shelter ourselves, thinking outside of the frame house box can yield benefits for generations to come.